OSLO,  Effective control of forest fires may prove crucial in the fight against global warming since blazes from Alaska to Indonesia spew out vast amounts of heat-trapping gases, Canadian foresters said on Thursday.

"Forests are a wild card in the debate" about rising world temperatures, said Brian Stocks, a forest fire expert with the government-run Canadian Forest Service.

Annual fire damage in countries from Russia to Canada varies hugely, and many of the most destructive blazes are lit by lightning in remote regions. But campers tipping over stoves or arsonists cause a rising number of preventable fires.

Stocks told Reuters that more careful forest plantings, better surveillance to spot outbreaks of fires, quicker response by fire-fighters and education of the public could limit damage.

Fires in Indonesia which raged for months in the late 1990s, creating clouds that dimmed the sun, released up to an estimated 2.6 billion tonnes of greenhouse gases or the equivalent of about 40 percent of world industrial emissions in a year.

Trees absorb carbon dioxide as they grow and release it when they burn or rot. Carbon dioxide is also emitted by burning fossil fuels in cars, power plants and factories, and is widely blamed for blanketing the planet and nudging up temperatures.

"Individuals should do everything possible to reduce energy use," Barry Waito, president of the Canadian Forestry Association, said in a statement.

But he also urged greater responsibility for managing forests. "Forests will play a central role in the extent of (climate) change future generations face," he said.

Many scientists say the buildup of carbon dioxide may spur less predictable weather, ranging from typhoons to heat waves, drive thousands of species of animals and plants to extinction by 2100 and drown low-lying coastal areas by raising sea levels.

BLAZES DOUBLE

In Canada, with about 10 percent of world forests, the area burned in the 1980s-90s roughly doubled from the 1970s, according to the National Forest Strategy Coalition which unites 67 groups from conservationists to government agencies.

And 60 percent of Canada's 8,500 annual forest fires are caused by humans, according to the coalition which meets in Toronto on Thursday and Friday. Rain forests, like in the Amazon, are wetter and so less vulnerable to fire.

Forest fires now release about 150 million tonnes of carbon dioxide a year in Canada, compared with a 2002 total of 730 million tonnes from industrial sources.

Under the U.N.'s Kyoto protocol, which entered into force last month despite a U.S. pullout, developed countries are meant to cut their industrial emissions of greenhouse gases by 5.2 percent below 1990 levels by 2008-12.

They are allowed to plant trees to help meet the goals, in addition to curbing use of fossil fuels and shifting to clean energy like wind or solar power.